Cirrocumulus clouds are called mackerel because its imagery. It looks like the scale of a mackerel fish. This cloud usually be seen during winter. It shows the fair yet cold weather.
Mackerel refers to a kind of a fish from the family of Scombridae. That’s why cirrocumulus clouds were compared to as a mackerel because the form of the said cloud is the sky is plain and looks like a scale. It appears mostly white but sometimes it also appears gray.